


A Non-Scientific Experiment

by ShamanicShaymin



Category: Undertale (Video Game)
Genre: Biting, Established Relationship, F/F, Masochism, Plot What Plot/Porn Without Plot, Rimming, Rough Kissing, Rough Sex, Scratching, Vaginal Fingering
Language: English
Status: Completed
Published: 2015-11-06
Updated: 2015-11-06
Packaged: 2018-04-30 06:56:36
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,575
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5154506
Author URL: https://archiveofourown.org/users/ShamanicShaymin/pseuds/ShamanicShaymin
Summary: <blockquote class="userstuff">
              <p>After watching one of her cheesy yaoi animes together, Alphys gets the courage to ask Undyne if they could try a particular kink.</p>
            </blockquote>





	A Non-Scientific Experiment

**Author's Note:**

  * For [naturalkillercyborg](https://archiveofourown.org/users/naturalkillercyborg/gifts).



> This is a late birthday present for my good friend Jean, who's been so good to me over the years. ;; In a way, it's also a thank-you gift for encouraging me to play Undertale. :)

The bed that folded into an extremely-easy-to-draw box got a lot of use in the lab these days.

"I-I... I'm so nervous..." Alphys stuttered. Her face was pinker than the shade of lipstick Mettaton advertised in the latest episode of his show, or all the battle skirts donned by her favorite magical girls. She bit her lip before deciding her pillow was the better option. Undyne hovered over the edge of the bed—and Alphys' back—in anticipation. A wide toothy grin spread on the fish captain's face, and she tightened her grip on the scientist's thighs.

"C'mon Alphys, this is gonna be great!" Undyne said. "We've been waiting FOREVER for this! We tried everything else, right?"

Alphys flinched. Even long before her self-esteem took a nose-dive after the lab experiments, the idea of rough play and masochism intrigued her (much to her embarrassment.) Undyne kept her nails long and sharp, and the way they bit into her flesh was... it hurt, but the scientist reveled in the sting of it. It fascinated her how something so painful could be so pleasurable.

Undyne lifted the dinosaur's tail, slowing down to stroke beneath its base. Alphys' mouth let go of the pillow, and she allowed herself to rest her forehead. Thankfully, she couldn't feel any drool... she always worried about drooling whenever she bit her pillow, though she never remembered feeling anything or if Undyne even cared. Alphys hugged her pillow and tensed again as her partner kneeled down close to her scaly skin. She felt the warmth of Undyne's breathing against her backside, brushing close to her back entrance...

Alphys gasped from the wetness of Undyne's tongue before immediately burying herself into her pillow and squeezing it hard. She winced, but after the initial shock, it didn't take long for the tension in her body to melt away and float like balloons in the sky. Her fingers loosened their grip and she slumped against the sheets. Undyne caressed the ring of muscle, lapping tenderly before sliding inside. In a way, it felt like being kissed, and Undyne kissed that sensitive spot—as well as the surrounding flesh—quite frequently. But the way the sea captain pushed past her defenses, stroking and circling inside her and spreading that heavenly heat... It was such a contrast to the way Undyne scratched her legs to pin her down. Blood trickled down the scientist's thighs as her partner's nails sunk deeper. So rough on the outside, but inside, Undyne was passionate, loving and devoted... and she loved every little thing about Alphys, even the parts the scientist considered unsavory about herself.

"Mmm... you have such a cute ass!" Undyne murmured. "Why didn't we do this sooner?"  
"Well... I-I was worried you might be grossed out. It's... ah... not exactly easy to talk about." Her partner continued her treatment while Alphys succumbed and sighed dreamily. One yaoi anime, Boku no Junjo Pornograph, had always been a guilty pleasure of hers. Only recently she garnered enough confidence to share it with Undyne, mainly to have a good laugh and also what she thought of a particular... _scene,_ where the Giant-Shouldered Glasses Dude (as Undyne called him) wanted to "seduce" the uke with his tongue. The sex itself, as predicted, was ridiculous and censored, but Alphys always wondered what the actual experience would be like. After pouring herself into her research one night, the scientist couldn't help but fantasize... what if she and Undyne did something like that together? Would she like it? Would Undyne be okay with it?

"I'm sure glad we did it! Those animes of yours have the coolest ideas!" Undyne tended to the dinosaur again, sucking and nipping the sensitive skin of her inner cheeks. "Mmmm... you're amazing... tasty too..." The fish captain withdrawn and let go of Alphys. The sea captain licked the crimson drops from her fingers, purposely mimicking the sly semes from Alphys' animes. As the metallic tinge teased her tongue, Alphys watched in rapture, and her eyes widened in eagerness as Undyne looked at her with mischievous intent. "Looks like I'm going to have to eat you all up!" The fish captain laughed.  
"Really...? I—I can't possibly taste _that_ good back there. Unless you mean..."  
“That's right!”

The sea captain lunged at Alphys and pinned her down, grabbing the scientist's wrists and holding them behind her back before sinking her teeth into her shoulders. Alphys squeaked, her partner marking her scaly skin with love bites and working and licking their way up. Fangs grazed her neck before clamping down, and the scientist groaned as Undyne sucked her fragile throat. Like a girl longing to be a princess at the ball, Alphys dreamed of being the damsel swept up in the arms of a dangerous but handsome vampire, growing faint as the mystical creature quenched their thirst for her. Undyne beat every blood-sucking bishounen and left them brooding behind. The prickling of the sea captain's bites dissolved into tingles of adrenaline bliss, and the dinosaur purposely squirmed to incite rougher action.

"Hey! Hold still!" Undyne shouted. The sea captain nipped her as she snuck her arms around the scientist's abdomen. Her callused hands slowed in their assault while possessing the dinosaur's breasts, kneading and scratching and indulging in their bulky softness. Alphys groaned, vocalizing her pleasure as her partner trailed more kisses and nibbles down her neck. Undyne rolled the scientist's nipples with her fingers again and again, feeling them peak against her touch. Then she pinched—hard—simultaneously sinking her fangs into Alphys with equal force.

Alphys screamed, and she wrenched her body to grab the sea captain's face. Undyne stared at her for a moment's confusion before Alphys pulled her in and shoved her lips against hers. The dinosaur took no mercy on her partner, probing and invading her mouth and leaving no place untouched. After a few startled grunts, Undyne finally caught up, eager to swallow her in return. Their tongues tangled violently as their bodies pushed against each other in a battle for dominance. Their lips bruised from the contact, but by the time the sea captain and the scientist parted for air, a different kind of ache consumed them.

"Undyne, I can't take this anymore!" Alphys cried. She shuffled around until she was behind Undyne, laying her down so her partner could have the pillow herself. "I want you..." The scientist said, diving her hand between Undyne's legs. "I want you so much!"  
"Yes...!" Undyne agreed. She stretched herself, tossing the pillow aside as she parted her thighs for easier access. "Let's do this!" She tossed her head and her cardinal-red ponytail went wild, groaning as the scientist's fingers searched her. She made no attempt to hide her thrill once Alphys found her clit, backing into the dinosaur to encourage her. "Yes... YES! You're amazing! More... more!"  
"Undyne... ah...!" Alphys worked her fingers in a frenzy, the small organ throbbing against them like it had a life of its own. The scientist moved her hand down, feeling how wet her partner was... her fingers thrust inside, and Undyne cheered her on for more. Alphys pushed herself against the sea captain, her scaly sweaty body covered in teeth marks and hickeys and bleeding scratches, and every cell of it hungry for Undyne. She added more fingers, and the sea captain plunged herself over them, riding them so fast the scientist could hardly keep up. Alphys whimpered, locking her legs around Undyne. As she did so, the scientist's own need brushed against smooth blue scales, and her hips moved on their own to fulfill it.

Screams filled the room, and the last thing Alphys was aware of was Undyne clenching around her fingers and the wonderful feeling that seized her body after she rubbed herself against Undyne... the dinosaur slouched against her partner, feeling weightless. Panting, Undyne turned to look at her, wrapping her arm around her shoulder. Miraculously, the bed still held itself together.

"Hehe... oh man!" The sea captain grinned. "You're something else, Alphys!"  
The scientist couldn't think of what to say, so she smiled back. No matter how many times they keep doing this, she still felt a little sheepish. Sheepish, but sated.  
"So, uh... what was that thing I did to you earlier?" Undyne asked. "Glasses Dude did it too, to the Wide-Eyed Blonde Dude—"  
"Oh, that?" Alphys blushed. "It's called 'rimming.' There's a lot of terms for it—some cruder than others—but that's the most common. I take it you liked it, huh?"  
"Hell yes! We should do it again!" Undyne cheered, squeezing her partner into a hug.  
"I... I'm glad." Alphys smiled again, returning the embrace.  
"You shouldn't be nervous about sharing your kinks with me, Alphys. Chances are, I'll like it too!" said Undyne. "If not, well, it's no big deal. There's tons of other stuff we can do! Speaking of kinks..." A cheeky smirk spread across the sea captain's face. "I heard about this spider chick who's really into bondage and stuff. Not just any old bondage! _Kinbaku_ or something like that. You wouldn't happen to know what it is, would you?"  
"As a matter of fact, I do! I think it's in a few of my Yu-Gi-Oh! BSMDX doujinshi."  
"We should look it up! After we rest a bit and tend to your cuts, maybe we can check it out. Sound good to you?"  
"Of course, Undyne." Alphys giggled. "Of course."


End file.
